Question

A non-inverting amplifier is working on 100 mV with input resistance of 400 and feedback resistance of 12012. Calculate its gain and output voltage.​

Answer 1

Explanation:

Concept:

Input offset voltage:

Whenever both the input terminals of the op-amp are grounded, ideally the output voltage must be zero. However, in this condition, the practical op-amp always shows a small non-zero output voltage.

The input offset voltage depends upon the temperature and given as:

Vid = V1 – V2

F1 T.S 22.7.20 Pallavi D4

Input Bias current:

F1 T.S 22.7.20 Pallavi D5

For ideal op-amp, no current flows into the input terminals but in a practical case, op-amp does have some very small input currents of the order 10-16 A to 10-14 A.

Therefore input bias current is defined as the current flowing into each of the two input terminals when they are biased to the same voltage level i.e. when the op-amp is balanced.

F1 T.S 22.7.20 Pallavi D5

Output offset voltage (Vo)offset due to input offset is given by:

Output offset voltage (Vo)offset due to input bias current is given by:

(Vo)offset = RfIB

Rf = Feedback resistor

R1 = Input resistance of the Op-Amp

Calculation:

Given:

Gain = 100, Vid = 6 mV, Ib = 500 nA

Output offset voltage (Vo)offset due to input offset is:

(VO)Offset = (1 + 100) 6mV

(VO)Offset = 606 mV

Output offset voltage (Vo)offset due to input bias current is:

(Vo)offset = RfIB

(VO)Offset = 47 kΩ × 500 nA

(VO)Offset = 23.5 mV

Answer 2

Answer:

Input offset voltage:

Whenever both the input terminals of the op-amp are grounded, ideally the output voltage must be zero. However, in this condition, the practical op-amp always shows a small non-zero output voltage.

The input offset voltage depends upon the temperature and given as:

Vid = V1 – V2